Supermarkets and pharmacies in unincorporated areas of Los Angeles County would have to stop offering plastic bags to customers by summer under a sweeping ban approved Tuesday by the Board of Supervisors.

The single-use plastic bag ban was introduced on a 3-1 vote, with Supervisor Mike Antonovich dissenting and Supervisor Don Knabe absent. It would take effect in July for larger markets and pharmacies, and January 2012 for all other stores.

Lawmakers hope it will cut in half the number of plastic bags that wind up in landfills, river beds, the ocean and other areas.

The ordinance also would require stores to charge customers 10 cents for each paper bag they use instead of the plastic variety. That fee would be retained by the stores to cover their costs for providing recyclable paper carryout bags and encouraging the use of reusable bags.

The ordinance will not apply to restaurant carry-out or food trucks. Customers receiving food stamps would be entitled to a free reusable or paper bag under the ordinance.

Stores in incorporated South Bay cities are not be affected by the ban. The law would apply only in unincorporated communities such as Lennox, Del Aire, El Camino Village, the county strip west of Carson and the La Rambla area surrounded by San Pedro.

Steve Scarpa, general manager of Cost Saver Market in an unincorporated area near Carson, said he is concerned he would lose business to nearby stores that wouldn’t have to abide by the new law.

“I think it’s kind of unfair,” Scarpa said. “Customers will just go to a store on the other side of Normandie Avenue that’s in a city so they don’t have to pay for bags. I think customers are going to be up in arms about it.”

Antonovich said he voted against the ban because he is concerned that it could have negative economic consequences.

“At a time of economic uncertainty, with a large number of businesses already leaving our state, it is not an appropriate time to impose this charge” on businesses and consumers, he said.

A county Department of Public Works staff report predicts the ban would slash the number of plastic bags used by each county household from the 2007 level of 1,600 to fewer than 800 by 2013. It would also save the county and local cities about $4 million in litter-reduction costs, and reduce by 50 percent the number of bags sent to landfills.

According to the environmental group Heal the Bay, which supported the ban, the state spends $25 million a year to collect and dispose of plastic bags. About 19 billion plastic bags are used in California each year, generating almost 150,000 tons of waste and killing marine animals and birds, according to the group.

“The environmental costs caused by these plastic bags are severe,” said county Public Works Director Gail Farber. “The cumulative effect is staggering.”

Heal the Bay and other advocates of the ban gathered outside the Hall of Administration before the meeting amid piles of hundreds of plastic bags.

“Something that we use for five minutes should not last for 500 years,” said actress and activist Amy Smart, to cheers from the crowd.

The vote was especially meaningful for Assemblywoman Julia Brownley, D-Santa Monica, who tried and failed to pass a statewide ban in August. Brownley has been an outspoken critic of the use of plastic bags, saying only a very small percentage are recycled and that they take hundreds of years to decompose.

“This is just the beginning of a wave of bans against single-use plastic bags across California,” Brownley said.

Proponents hope the move will spur other cities to adopt similar measures. Malibu, San Francisco, Palo Alto and Fairfax have also passed bans on single-use plastic bags.

Other California communities such as Santa Monica, Marin, San Jose and Santa Clara also are considering bans this year.

Manhattan Beach was sued in July 2008 by the Save the Bag Coalition, a group representing plastic manufacturers, after passing an ordinance to ban the carry-out bags. The group argued the city violated the California Environmental Quality Act by not fully analyzing the ban’s effects.

In February 2009, a Los Angeles Superior Court judge rejected the city’s ban, ruling that the city should have first fully studied its potential environmental consequences. The city appealed the ruling, which was upheld by an appellate court earlier this year. The case is expected to reach the state Supreme Court in 2011.

Opponents of the county’s measure argued that banning plastic bags will raise grocery costs for families, seniors and the unemployed, who are already struggling in a tough economy.

Monique Gillaspie, a 27-year-old Lomita resident shopping Tuesday in an unincorporated area near Carson, said she doesn’t like the ban.

“I think it’s awful,” she said. “For one, you have to pay extra for a paper bag. And how many trees are they going to destroy? Plastic bags can be recycled. They will take away from my pleasure of shopping.”

Others argued that the ban would cost jobs.

Adrian Backer, president of the California Film Extruders and Converters Association, said 2,300 jobs at plastic bag manufacturers statewide were at risk, and thousands more at suppliers. Los Angeles County is home to some of California’s leading plastic bag manufacturers, Backer said.

“If this ordinance becomes law, we have to ask how many small businesses will be hurt,” said George Kivett, chairman of the South Bay Association of Chambers of Commerce.

The board has been working to reduce the use of plastic bags through voluntary programs since at least 2008. In July, the advocacy group Environment California presented the board with 1,800 signatures in support of an outright ban.

County officials also plan to urge the 88 cities within the county to adopt similar ordinances. Until then, they would not be subject to the ban. Los Angeles and Culver City are already moving toward bans.

“The wave is beginning here and hopefully it will be moving all the way up to Sacramento,” said Supervisor Gloria Molina.

Sandy Mazza is a freelancer. She previously worked for Southern California News Group as a city reporter covering Carson and Hawthorne and specializing in features about Los Angeles' growing Silicon Beach tech, bioscience, and aerospace sectors.